3-Acetyl-(1,2 -a)imidazo-1,4-benzodiazepines

ABSTRACT

Novel 1H-1,4-benzodiazepines bearing between the 1,2-positions an imidazo ring. These novel benzodiazepines are useful as muscle relaxant, anti-convulsant and sedative agents.

United States Patent 1 Derieg et al.

[ Apr. 1, 1975 3-ACETYL-( 1,2

-A )IMlDAZO-l ,4-BENZODIAZEPINES [75] Inventors: Michael Edward Derieg, Caldwell;

Rodney Ian Fryer, North Caldwell; Leo Henryk Sternbach, Upper Montclair, all of NJ.

[73] Assignee: Hoffmann-La Roche Inc., Nutley,

[22] Filed: Nov. 28, 1973 [2]] Appl. No.: 419,564

Related US. Application Data [62] Division of Ser. No. 210,253, Dec. 20, 1971, Pat. No.

[52] U.S. Cl. 260/309.7 [51] Int. Cl C07d 49/34 [58] Field of Search 260/3097 [56] References Cited UNITED STATES PATENTS 3,734,912 5/1973 I-lanze 260/2565 R OTHER PUBLICATIONS Derieg et al., J. Med. Chem., 1968, 11 (4), 912-913. C.A. 69:36092V (1968). CA. 70:87862Z (1969).

Primary ExaminerLewis Gotts Assistant Examiner-Ethel G. Love Attorney, Agent, or Firm-Samuel L. Welt; Bernard S. Leon 2 Claims, No Drawings 1 3-ACETYL-(1.2+a) IMIDAZO-l ,4-BENZODIAZEPINES RELATED APPLICATIONS This application is a divisional application of copending application Ser. No. 210,253, filed Dec. 20, 1971, now US. Pat. No. 3,796,713.

DETAILED DESCRIPTION OF INVENTION The present invention relates to 1,2-heterocyclic-ll-I- 1,4-benzodiazepines. More particularly, the invention concerns 1,4-benzodiazepines which bear a 5- or 6- membered heterocyclic ring between positions 1- and 2- and a C=C grouping in positions 2-3. The invention further comprehends processes for making these novel benzodiazepines.

More specifically, the compounds of the present invention are selected from the group consisting of compounds of the general formula n is the integer O or 1; R, and R are selected from the group consisting of halogen, hydrogen, trifluoromethyl, nitro, lower alkyl, and cyano; R R are each selected from the group consisting of hydrogen and lower alkyl; R, signifies lower alkyl and R is selected from the group consisting of pyridyl, phenyl or halophenyl.

As used herein, the term lower alkyl refers to straightand branched chain hydrocarbon groups containing from 1 to 4 carbon atoms such as, for example, methyl, ethyl, propyl, isopropyl, butyl and the like. The term halogen refers to all four forms thereof, i.e.,

bromine, chlorine, fluorine and iodine. When the R substituent is pyridyl, the 2-pyridyl group is preferred. When the R substituent is a halophenyl group, the o'-halophenyl group is preferred.

A preferred class of compounds falling within the scope of formula 1 above are those wherein R signifies nitro or halogen, preferably chlorine, and is located in the 7-position of the basic benzodiazepine molecule, R is hydrogen, A is the group wherein R is phenyl or halophenyl, i.e., compounds of the formula Fl -CH E 6 l n-co-R N c 7 R /C- 3 Ia R1 c N I wherein R is nitro or halogen, preferably chlorine; R is hydrogen or halogen, preferably chlorine or fluorine; n and R R are as described above.

Another preferred class of compounds falling within the scope of formula I above are those wherein R is nitro or halogen, preferably chlorine, and is located in the 7-position of the basic benzodiazepine molecule, R -R are hydrogen, and A is the group wherein R is phenyl or halophenyl i.e., compounds of the formula ca 11 c 2 m-co-n c N I 1 wherein R R R and n are as described above.

The most preferred compounds of formula I above are:

3-acetyl-8-chloro-6-(2-fiuorophenyl)-2,3-dihydrolI-l-imidazo [l,2-a][1,4]benzodiazepine;

4-acetyl-9-chloro-7-( 2-fluorophenyl)-l ,2,3 ,4- tetrahydropyrimido( 1 ,2'-a)( l ,4)benzodiazepine;

4-acetyl-9-chloro-l ,2,3 ,4-tetrahydro-7- phenylpyrimido( 1,2-a) 1,4)benzodiazepine.

The compounds of formula 1 above may be prepared by reacting a compound of the formula 3 is (Cl l CHR6 R 4w l u N H N 2 cua 1 wherein R -R A and n are as described above with an acid anhydride of a carboxylic acid having from 2-5 carbon atoms.

Examples of acid anhydrides that can be employed in the preparation of the desired end products of formula I include acetic anhydride, propionic anhydride, butyric anhydride and the like.

The reaction between the compound of formula II and the acid anhydride may be effected in the presence of an inert organic solvent; suitable solvents for this purpose include aromatic hydrocarbons such as benzene, toluene and the like, chlorinated hydrocarbons such as chloroform, methylene chloride and the like, and dimethylformamide (DMF). When the A substituent in the starting material of formula II is a group, R defined as above, then the reaction can be conducted at a temperature in the range of about 0C to room temperature. In either case, the reaction between the formula II compound and the acid anhydride is preferably conducted at room temperature. Pressure is not critical to this reaction and thus for the sake of convenience the reaction is effected at atmospheric pressure.

The starting materials of formula II above are known compounds or can be prepared in analogy to the preparation of the known compounds.

The compounds of formula I above are useful as anticonvulsants, muscle relaxants and sedatives. Thus these compounds can be used as medicaments. For example, they can be used in the form of pharmaceutical preparations which contain them in admixture with a pharmaceutical, organic or inorganic carrier material which is suitable for enteral or parenteral application such as, for example, gelatin, lactose, starches, magnesium stearate, talc, vegetable oils, gum arabic, polyalkylene glycols, Vaseline, etc. The pharmaceutical preparations can be prepared in solid form (e.g., as tablets, dragees, suppositories, capsules) or in liquid form (e.g., as solutions, suspensions or emulsions). They can also contain other therapeutically valuable substances.

The compounds of formula I above can be administered at dosages adjusted to individual requirements and fitted to the pharmaceutical exigencies of the situation. Convenient pharmaceutical dosages are in the range of from about 2 mg. to about 200 mg. per day.

The useful anti-convulsant activity of the compounds of this invention is shown in warm-blooded animals utilizing the standard antimetrazole test. In the antimetrazole test, a compound is administered orally to groups of four mice at various dose levels. One hour later, metrazole is administered subcutaneously and the animals are observed for protection from convulsire seizures. Results are recorded as the number of animals protected against convulsions. The dose at which 50% of the animals are protected from convulsive seizures is expressed as the ED Following these test procedures, compounds such as 4-acetyl-9-chloro-l,2,3,4- tetrahydro-7-phenylpyrimido( 1,2- a)(l,4)benzodiazepine and 3-acetyl-8-chloro-6-(2- fluorophenyl)-2,3-dihydrol H-imidazo[ 1,2- a][l,4]benzodiazepine show an Ed of 93.0: 6.74 and 3.1i 0.3 mg./kg. respectively, indicating that these compounds exhibit anti-convulsant activity.

The sedative and muscle relaxant activity of the compounds of the invention is shown using the standard foot shock test. In this test, a pair of mice is confined under a l-liter beaker placed on a grid which presents shock to the feet. At least five fighting episodes are elicited in a 2-minute period. Pairs of mice are marked and pretreated 1 hour prior to a second shocking. Logarithmic dose intervals are utilized up to a maximum of 10 mg./kg. At the percent blocking dose 3 out of three pairs must be blocked from fighting. The measurements are made at the dose level at which 100% blocking is observed and the results are expressed as the dose in mg./kg. which block the fighting response for one hour. Following these test procedures, 4-acetyl- 9-chloro-7-( 2-fluorophenyl l ,2,3 ,4-tetrahydropyrimido[ l,2-a][ l,4]benzodiazepine exhibited a PD of 20 mg./kg. and 3-acetyl-8-chloro-6-(2- fluorophenyl)-2,3-dihydro-l H-imidazo[ 1,2- a][l,4]benzodiazepine exhibited a PD of 10 mg./kg.

The following examples are illustrative of the present invention. All temperatures given are in degrees centigrade.

EXAMPLE 1 Preparation of 3-acetyl-8-chloro-6-(2-fluorophenyl)- 2,3-dihydro lH-imidazo[ 1,2-a] l ,4]benzodiazepine A solution of l g (3,2 mmol) of 8-chloro-6-(2- fluorophenyl 1 ,2-dihydro-4H-imidazo[ 1,2- a][l,4]benzodiazepine in 10 ml of acetic anhydride was stirred for 2 hours at room temperature. The red precipitate was separated by filtration and the damp solid was stored over night under reduced pressure to remove the solvent. The above-named product was obtained as a red crystalline solid, mp. 166-l69.

EXAMPLE 2 Preparation of 4-acetyl-9-chloro-1,2,3,4-tetrahydro-7- phenyl-pyrimido[ 1,2-a] 1,4]benzodiazepine tetrahydropyrimido-( l ,2-a)( 1,4)benzdiazepine A solution of 25 ml of acetic anhydride and 5.0 g (16.1 mmol) of 9-chloro-l,2,3,5-tetrahydro-7-phenylpyrido[3,2-a][1,4]benzodiazepine was stirred for 15 minutes by which time a bright orange solid had formed. The above-named product was obtained by fil- 5 tration in crystalline form, mp 21 12l5. Recrystallization from chloroform/hexane gave orange prisms, m.p. 224-225.

EXAMPLE 3 EXAMPLE 4 4-Acetyl-9-chloro-7-(2-f1uorophenyl)-1,2,3,4-tetrahydropyrimido( l,2-a)( 1,4 )benzodiazepine Suppository Formulation Per 1 .3 Gm. Suppository pine Wecobee M* Carnauba Wax 1.245 Gm. 0.045 Gm.

E. F. Drew Company, 522 Fifth Avenue, New York, New York.

Procedure:

l. The Wecobee M and the carnauba wax were melted in a suitable size glass-lined container (stainless steel may also be used), mixed well and cooled to 45C.

2. The 4-acetyl-9-ch1oro-7-(2-fluorophenyl)-l,2,3,4- tetrahydropyrimido( l,2-a)( 1,4)benzodiazepine which has been reduced to a fine powder with no lumps, was added and stirred until completely and uniformly dispersed.

3. The mixture was poured into suppository molds to yield suppositories having an individual weight of 1.3 grams.

4. The suppositories were cooled and removed from molds. They were then individually wrapped in wax paper for packaging (foil may also be used).

EXAMPLE 5 4-Acetyl-9-chloro-7-(2-fluorophenyl)-1,2,3,4-

Capsule Formulation Per capsule 4-acetyl-9-chloro-7-(2-fluorophenyl)- 1,2,3,4-tetrahydropyrimido( l ,2-a)

Procedure:

1. 4-Acetyl-9-chloro-7-(2-fluorophenyl)-l ,2,3 ,4- tetrahydropyrimido l ,2-a)( 1,4)benzodiazepine, lactose and corn starch were mixed in a suitable manner.

2. The mixture was further blended by passing through a Fitzpatrick Comminuting Machine withh a No. 1A screen with knives forward.

3. The blended powder was returned to the mixer, the tale added and blended thoroughly.

4. The mixture was filled into No. 4 hard shell gelatin capsules on a Parke Davis capsulating machine. (Any similar type capsulating machine may be used.)

EXAMPLE 6 4-Acetyl-9-chloro-7-( 2-fluorophenyl)-1 ,2,3,4-tetrahydropyrimido( l,2-a)( 1,4)benzodiazepine Tablet Formulation Per Tablet 1,2,3,4-tetrahydropyrimido( 1,2-a)( 1,4)

benzodiaze ine 25.00 mg.

Dicalcium Phosphate Dihydrate, Unmilled 175.00 mg.

Corn Starch 24.00 mg.

Magnesium Stearate 1.00 m Total Weight 225.00 mg.

Procedure:

1. 4-Acetyl-9-chloro-7-(2-fluorophenyl)-1,2,3 ,4- tetrahydropyrimido l,2-a)(1,4)benzodiazepine and corn starch were mixed together and passed through a No. 00 screen in Model J-Fitzmill with hammers forward.

2. This premix was then mixed with dicalcium phosphate and one-half of the magnesium stearate, passed through a No. 1A screen in Model J-Fitzmill with knives forward, and slugged.

3. The slugs were passed through a No. 2A plate in a Model D-Fitzmill at slow speed with knives forward, and the remaining magnesium stearate was added.

4. .The mixture was mixed and compressed.

We claim:

1. A compound of the formula N-CO-lower a1 ky l halogen wherein R signifies hydrogen or a lower alkyl group having from 1 to 4-carbon atoms and R signifies hydrogen or halogen.

2. The compound of claim 1 of the formula 3-acetyl- 8-chloro-6-( 2-fluorophenyl )-2,3-dihydrol H-imidazo 

1. A COMPOUND OF THE FORMULA
 2. The compound of claim 1 of the formula 3-acetyl-8-chloro-6-(2-fluorophenyl)-2,3-dihydro-1H-imidazo (1,2-a)(1, 4)benzodiazepine. 